喷雾干燥条件对荔枝酸奶粉乳酸菌存活率及粉体特性的影响

Effect of spray drying parameters on survival rate of lactic acid bacteria and physical properties of lychee yogurt powder

为了探明喷雾干燥条件对荔枝酸奶粉乳酸菌存活率及粉体特性的影响规律,采用喷雾干燥法对荔枝酸奶进行微胶囊化。探讨料液固形物含量、进风温度、进料速度对荔枝酸奶粉的乳酸菌存活率、水分含量和得率的影响,在较优喷雾干燥条件下,进一步探讨保护剂海藻糖对产品品质的影响。结果显示,当料液固形物含量25%~30%,进风温度140℃,进料速度6.5~10.0 m L/min时,荔枝酸奶粉的乳酸菌存活率、得率均高于50%,且水分含量较低(4.66%~4.79%)。在此条件下,添加6%(以酸奶质量计)的海藻糖可将乳酸菌存活率提高至73.94%(6.34×10~8CFU/g),水分含量为4.72%,得率37.79%;扫描电子显微镜(SEM)观察发现,与不添加海藻糖的相比,添加6%海藻糖的荔枝酸奶粉颗粒表面圆润且裂纹较小;差示扫描量热法(DSC)测得粉体的玻璃化转变温度Tg为71.61℃。

The objective of this study was to explore the influencing regularities of spray drying parameters on the survival rate of microeneapsulated lactic acid bacteria in lychee yoghurt powder and its physical properties.Effects of feed concentration, inlet temperature,feeding rate on survival rate of lactic acid bacteria, moisture content and yield of lychee yoghurt powder microencapsulated by spray drying were investigated. Under the better spray drying condition, the influences of trehalose on production quality were further investigated. The results showed that with 25%-30% feed concentration, 140 ℃ inlet air temperature,6.5-10.0 mL/min pump rate, the lyehee yoghurt powder illustrated the high survival rate of lactic acid bacteria and yield（ 〉50% ）, and the low moisture content （4.66%-4.79% ）.Under this condition, the survival rate of lactic acid bacteria,moisture content and yield reached 73.94% （6.34 × 10^8 CFU/g） ,4.72% and 37.79% respectively with 6% trehalose added.Scanning electron microscopy（SEM） photographs showed that the addition of 6% （w/w）trehalose made particles more rounded surfaces and smaller cracks than the control. The probiotic powder was further analyzed using differential scanning calorimetry（DSC） , the glass transition temperature Tg = 71.61 ℃.